1. Field of the Invention
The present invention generally relates to techniques for characterizing a transmitter and, more particularly, is concerned with a system and method for identifying and validating a transmitter by extracting and analyzing both an identification (ID) code and a signal characteristic.
2. Description of the Prior Art
In some known prior art communications systems, individual transmitters are assigned identification (ID) code in order to validate their use of the network. Typically these ID codes accompany other communications transmitted by the transmitter. In the case of cellular telephone systems, the absence of a valid ID code is used to detect invalid transmitters on the network so that steps can be taken to lock them out of the network without disrupting service to legitimate users.
In other known prior art communications systems, such as disclosed in U.S. Pat. No. 5,005,210 to Ferrell, one or more parameters of a transient signal transmitted by the transmitter is used to identify and verify the particular transmitter. However, neither of these prior art communications systems embody the necessary levels of security required to ensure the reliability of the identification and validation process.
Consequently, a need still exists for an improved technique for ensuring reliability of the identification and validation process.